Mark TASK-0021..TASK-0024 complete in task management

Refactor router handle_message into phase helpers (TASK-0024)

Derive default TOTP policy from command auth metadata (TASK-0023)

Unify bang shortcut parsing across router and DM handlers (TASK-0022)

Prune unused registry and DM admin helper symbols (TASK-0021)

Add detailed immediate TODO tasks for complexity review follow-ups

feat(router): remove compat retry path and complete TODO 0012-0014

-m Task update

feat(sessions): enforce scoped single-session and add stale purge

chore(tasks): add TASK-0019 for single-session scope behavior

feat(state): add prefixed session artifacts and purge controls

feat(logging): unify session jsonl logs with archival rotation

docs: note sandbox network requirement for git push

Add .test file

Simplify inactive-session choice flow and add continue shortcuts